This could also be the cause of some of your issues as well. What you may think is slow response/garbled data may be caused by fact that Serial Communications on RFX9600 with current ProntoScript implementation has a limitation. You cannot send without clearing the receive buffer on the UART.
I'm aware of that limitation, and I'm pretty convinced this is not the issue. After I do one send, I asynchronously wait for a full and complete response before I do the next send. I have tried with the timeout set to 5000 (5 seconds), so I know I am receiving all data. (If I were to lose data, the extreme timeout would make the dropouts obvious and easy humanly noticeable). I have also tried doing synchronous communication, but the result is the same.